If you think you can qualify to be an astronaut, you have stiff competition. More than 6,300 people applied to join the ranks of NASA astronauts in 2012. That was twice as many as the space agency usually receives, and the most since 1978. Astronauts work either as pilots who fly spacecraft or as mission specialists who conduct experiments. Regardless of their position, astronauts need certain qualities to survive both NASA’s selection process and space travel itself.

Intelligence

Astronauts need above-average intelligence. NASA isn’t looking for book smarts alone, though formal training is important. Rather, astronauts need quick thinking to handle unexpected problems. They also need the intellectual creativity to dream up new avenues of space-based research into medicine, materials and processes for use on Earth and in space. Curiosity is key, as are people skills and communication skills.

Adaptability

Astronauts have many responsibilities in space. They need the flexibility to move from one task to another, different task. They also work on teams with astronauts from other countries and cultures, so they must be open-minded to diversity. They must be willing to change routines to accommodate new procedures.

Physical Condition

The rigors of space travel are just about as intense as the rigors of space training. To ensure mission fitness, NASA requires astronaut candidates to pass a physical similar to a military physical. Astronauts need eyesight of 20/100 or better uncorrected, correctable to 20/20 in each eye. Their blood pressure can’t be above 140/90. They must be between 58 1/2 and 75 inches tall. Candidates also must meet military water survival standards, which test for the ability to swim without stopping and to swim and tread water clothed in flight gear. Astronauts also must be SCUBA-qualified to prepare for spacewalk training. Their bodies must respond well to high and low atmospheric pressures. They also must be prepared for the physical effects of zero gravity training up to 40 times a day. Space travel can last for months, during which the human body must function amid physical stress.

Mental Endurance

Astronauts who make it through the physical demands of space travel must also grapple with isolation, fear and separation from loved ones. It’s not easy to live in close quarters with virtual strangers for three to six months or more. Astronauts must begin to cope with those long periods away from home during training, which takes two to three years and requires heavy travel to practice with international mission partners.

Education

Astronauts need a bachelor’s degree from an accredited university in engineering, biological science, physical science or math. NASA prefers candidates with advanced degrees. Astronauts also need at least three years of increasingly responsible professional experience in their major field, or at least 1,000 hours working as a pilot in command of jet airplanes. NASA also considers teaching experience at the K-12 level qualifying experience for astronaut candidates, and the agency encourages teachers to apply. To graduate from candidate school and become an astronaut, prospects must pass International Space Station systems training, extravehicular activity skills training, robotics skills training, Russian language training and aircraft flight readiness training.